It?s estimated there are 200-thousand Sudanese refugees in eastern Chad. Since early this year, they have fled the fighting in Sudan?s Darfur region. When they arrived in Chad, many of the refugees were obviously in poor health. But to get a more scientific profile on their condition, the Un and humanitarian groups worked with the US Centers for Disease Control, or CDC.

The survey found that of the Sudanese children between the ages of six months and five years, 36 to 39 percent were malnourished and 35 to 58 percent had diarrhea. Many children also lacked measles vaccinations.

Basia Tomczyk is an epidemiologist with the CDC in Atlanta and recently helped conduct a health survey in northeastern Chad. She spoke to English to Africa reporter Joe De Capua about how the research was done.

She says, ?Initially, we were asked to conduct a very large survey along the border. Because obviously you want to sample a little bit of everybody so you can walk away saying this is representative of all the refugees in Chad. However, when you actually go to the field to conduct survey research you start to address some of the constraints, such as logistics, money, the environmental issues, the rainy season, etc. So, you start using some of these things to then define your population of interest for that particular survey.?

Ms. Tomczyk says one of the important measurements used is the height for weight ratio. In other words, is a child?s weight in line with his or her height? If they weigh too little, it is a sign of malnutrition. She says it is much more accurate than simply looking at a child. She says besides food, the refugees in eastern Chad also need better health care, clean water and sanitation.